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Biomedical subjects

H Murata

Publications and source records attributed to H Murata.

At least 163 records · Page 9Linked to original sources
PubMed1996

Common T cell receptor clonotype in lacrimal glands and labial salivary glands from patients with Sjögren's syndrome.

Sjogren's syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration into lacrimal and salivary glands leading to symptomatic dry eyes and mouth. Immunohistological studies have clarified that the majority of infiltrating lymphocytes around the lacrimal glands and labial salivary glands are CD4 positive alphabeta T cells. To analyze the pathogenesis of T cells infiltrating into lacrimal and labial salivary glands, we examined T cell clonotype of these cells in both glands from four SS patients using PCR-single-strand conformation polymorphism (SSCP) and a sequencing method. SSCP analysis showed that some infiltrating T cells in both glands expand clonally, suggesting that the cells proliferate by antigen-driven stimulation. Intriguingly, six to sixteen identical T cell receptor (TCR) Vbeta genes were commonly found in lacrimal glands and labial salivary glands from individual patients. This indicates that some T cells infiltrating into both glands recognize the shared epitopes on autoantigens. Moreover, highly conserved amino acid sequence motifs were found in the TCR CDR3 region bearing the same TCR Vbeta family gene from four SS patients, supporting the notion that the shared epitopes on antigens are limited. In conclusion, these findings suggest that some autoreactive T cells infiltrating into the lips and eyes recognized restricted epitopes of a common autoantigen in patients with SS.

Amino Acid Sequence↗
PubMed1996

Increased frequency of HLA DR13 in hepatitis C virus carriers with persistently normal ALT levels.

The aim of this study was to clarify the relationship between human leukocyte antigen DR allele distribution and the degree of liver cell injury of hepatitis C virus (HCV) carriers in Japan. The subjects, 68 HCV carriers, were divided into two groups according to the laboratory data and liver histology. Those in the asymptomatic carrier group (n = 19) had normal ALT levels persistently for 8-153 months (mean 25.7 months) and were diagnosed histologically as normal liver, nonspecific reactive hepatitis or chronic persistent hepatitis. Those in the chronic active hepatitis group (n = 49) had elevated ALT levels and were diagnosed histologically with chronic active hepatitis. The human leukocyte antigen DR alleles of all subjects were defined using the polymerase chain reaction restriction fragment length polymorphism method. The expression of human leukocyte antigen class I antigen and intercellular adhesion molecule 1 on the hepatocyte membrane were also examined in 14 patients from each group using an indirect immunohistochemical method. The frequency of DR13 (42.1%) in the asymptomatic carrier group was significantly higher (Pc < 0.003) than that of the chronic active hepatitis group (4.1%). There were no significant differences for the other DR alleles. The frequencies of expression of human leukocyte antigen class I antigen and intercellular adhesion molecule 1 on the hepatocyte membrane of the asymptomatic carrier group were significantly less than those of the chronic hepatitis group (64% vs. 100% P < 0.05, 29% vs. 71% P < 0.05, respectively), although there was no significant difference in the serum HCV-RNA titer between the two groups (10(6.4 +/- 1.1) vs. 10(6.5 +/- 0.7) copies/mL). These results demonstrate that the cellular immune response of the asymptomatic carrier group is less activated than the response of the chronic active hepatitis group and that HLA DR13 may be closely associated with this low activity of hepatitis among HCV carriers.

Adult↗
PubMed1996

Mass spectrometric screening method for microcystins in cyanobacteria.

A screening method for microcystins in cyanobacteria, which consists of the formation of 3-methoxy-2-methyl-4-phenylbutyric acid as an oxidation product of microcystins by ozonolysis, and detection of 3-methoxy-2-methyl-4-phenylbutyric acid by thermospray-liquid chromatography/mass spectrometry or electron ionization-gas chromatography/mass spectrometry using selected ion monitoring, was developed. The ozonolysis made it possible to significantly reduce the formation times of 3-methoxy-2-methyl-4-phenylbutyric acid because the previously required extraction, clean-up and other procedures could be entirely eliminated. The resulting intact 2-methyl-4-phenylbutyric acid was directly analyzed by thermospray-liquid or electron ionization-gas chromatography/mass spectrometry, and the procedures from ozonolysis to analysis of microcystins at the pmole levels were performed within only 30 min. The calibration curves obtained by thermospray-liquid or electron ionization-gas chromatography/mass spectrometry analysis showed a linear relationship from 14 to 830 pmole and from 2.5 to 100 pmole of microcystin-LR, respectively. The method was applied to the detection and determination of the total amount of microcystins in bloom and cultured samples, showing that it provided a means of not only screening for microcystins but of their accurate quantitation.

Calibration↗
PubMed1996

The influence of immersion solutions on the viscoelasticity of temporary soft lining materials.

OBJECTIVES: The purpose of this study was to examine the influence of laboratory immersion in a number of solvents on the viscoelasticity of temporary soft lining materials. It was an initial attempt to reproduce the changes seen clinically with a view to formulating more clinically relevant immersion regimes for the evaluation of these materials. METHODS: Changes in the viscoelasticity of four temporary soft lining materials following immersion at 37 + or - 1 degree C in 10% acetone/90% water, 20A% acetone/80% water and hexane was compared to a control immersion in distilled water using a penetrometer modified to record creep strain and strain during recovery. Testing was performed at 2 h and 24 h and then at 2, 4, 7, 21 and 28 d after sample preparation. Summary measures were used to describe individual specimen changes in derived values of initial and time dependent compliance and elastic recovery from 0-7, 7-28 and 0-28 d. RESULTS: Immersion in hexane resulted in at least a 50% reduction in compliance of 28 d. There was a significantly greater reduction in compliance for hexane immersion than for any other solvent (p<0.01). Immersion in 20% acetone resulted in an increase in compliance of around 1 mm/N after 1 wk compared with a reduction of up to 1 mm/N in distilled water. There was a reduction in elastic recovery for 3 out of 4 materials with 20% acetone/80% water solution. Changes in elastic recovery were smaller than those of compliance. SIGNIFICANCE: The reduction in compliance with hexane immersion suggests that this, or similar solvents, may form the basis of more clinically relevant immersion regimes. This may contribute to the development of improved temporary soft lining materials.

Acetone↗
PubMed1996

Uncoupling mechanism of glycoside antibiotic aculeximycin in isolated rat-liver mitochondria.

Effects of basic glycoside antibiotic aculeximycin (ACM) on the oxidative phosphorylation of rat-liver mitochondria were examined. ACM was shown to be a potent uncoupler of the oxidative phosphorylation. To cause the same extent of respiration release, higher concentration of ACM was required in phosphate (Pi)-free medium than in Pi medium. During the uncoupling caused by ACM in Pi medium, large amplitude swelling and oxidation of intramitochondrial NAD(P)H occurred, indicating that ACM remarkably enhances permeability of the inner mitochondrial membrane. The Pi uptake via Pi/H+ symporter was shown to play an important, but not essential, role in the uncoupling by ACM, indicating the increase in membrane permeability is mostly due to acceleration of Pi/H+ influx through Pi/H+ symporter activated by ACM. ACM is the first naturally occurring antibiotic, to our knowledge, which activates Pi/H+ symporter. However, since the inhibition of Pi/H+ symporter by N-ethylmaleimide did not completely abolish the uncoupling activity of ACM, and ACM induced the uncoupling even in Pi-free medium, an increase in the membrane permeability for other ions, such as Na+ and K+, due to a different action mechanism has also to be considered. On the other hand, positively charged amine local anesthetics, like dibucaine, prevented the uncoupling activity by ACM in both Pi and Pi-free medium. The uncoupling activity of N-diacetylated ACM lacking free amino groups was ca. 1/120th that of ACM, indicating that positively charged amino groups are important for the uncoupling activity. It is suggested that some specific interactions between positively charged amino groups of ACM and the binding site, which is probably negatively charged, are triggers that affect the permeability of the inner mitochondrial membrane. Amine local anesthetics may mask the negative charge of the binding site, thereby interfering with ACM binding.

Animals↗
PubMed1996

Analysis of composition and structure of hard autopolymerizing reline resins.

The authors investigated the composition and structure of six hard auto-polymerizing reline resins. The chemical compositions, glass transition temperatures, molecular weights and particle size distributions of the powders, and the chemical compositions of the liquids were examined. The powder compositions were classified into three groups. The first group contained poly(methyl methacrylate). The second contained poly(ethyl methacrylate) and poly(methyl methacrylate/ethyl methacrylate) and the third contained poly(ethyl methacrylate). The average molecular weights of these powders was about 2 x 10(5). The indexes of molecular weight dispersion suggested that all powders contained polymers that had a narrow molecular weight distribution. The particle size distribution of these powders was classified into two groups. The first group was mainly in the range of 50-100 microns and the second mainly between 20 and 50 microns. The composition of the liquids was classified into three groups. The first group contained a monofunctional methacrylate monomer. The second contained a monofunctional methacrylate monomer and a plasticizer and the third contained monofunctional methacrylate monomers and cross-linking agents. The results of this experiment showed the differences in composition among the products. This will be useful for examining the relationship between the composition and mechanical properties of hard autopolymerizing reline resins.

Acrylic Resins↗
PubMed1996

The effects of cross-linking agents on the water sorption and solubility characteristics of denture base resin.

Six different cross-linking agents were added to the monomer component of an autopolymerizing denture base resin, and their effects on the water sorption and solubility were investigated. The results of this study suggested that the chemical nature of the polymer versus that of the water molecule directly affected the water sorption of denture base resin. The addition of a cross-linking agent decreased the solubility with increasing concentration.

Acrylic Resins↗
PubMed1996

Fluoridation of hydroxyapatite powder by ammonium hexafluorosilicate.

Diamine silver fluoride [AgF: (NH3)2AgF] is a unique fluoride solution used clinically in Japan for primary teeth. AgF has been shown to reduce dental caries and dentine hypersensitivity. However, AgF also stains teeth black due to sulfide precipitation and thus is unacceptable for permanent teeth. In the present study, the potential value of ammonium hexafluorosilicate [SiF: (NH4)2SiF6], which has a formula similar to that of AgF but contains no Ag, was studied with respect to its ability to fluoridate apatite. Hydroxyapatite [HAP: Ca10(PO4)6(OH)2] powder was treated with several topical fluoride solutions, i.e. neutral sodium fluoride, acidulated phosphate fluoride (APF) along with AgF and SiF. Following treatment, the HAP powders were analyzed for their fluorine content, crystallinity changes, and solubility in acidic solution. The highest level of fluoridated HAP [FAP: Ca10(PO4)6(OH)xF2-x] was observed in HAP powder treated with SiF, even though more total fluorine in the form of FAP and CaF2 was observed in HAP powder samples treated with APF. Presumably as a consequence of this higher level of FAP formation after SiF treatment, the highest level of crystallinity along with the lowest solubility in acidic solution were observed in HAP powder treated with SiF solution. We concluded, therefore, that SiF may have potential value for use as a topical fluoride solution.

Acidulated Phosphate Fluoride↗
PubMed1996

Effects of nitroglycerin on vasospasm and cyclic nucleotides in a primate model of subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Nitroglycerin, as well as nitric oxide, causes hyperpolarization and cGMP elevation in vascular smooth muscle cells. It is unknown whether nitroglycerin ameliorates vasospasm by an increase in cGMP levels after subarachnoid hemorrhage (SAH). The purpose of the present study was to measure the levels of both cGMP and cAMP in the cerebral arteries and parietal cerebral cortices in a primate model and to determine the effect of nitroglycerin on vasospasm after SAH. METHODS: Chronic vasospasm was induced by clot placement around the right middle cerebral artery (MCA). Seven days after the surgery, angiography was repeated and either nitroglycerin (3 micrograms/kg per hour) or saline was administered intravenously. Angiography and regional cerebral blood flow (rCBF) measurements in the bilateral parietal cortices were performed before and after each treatment. Both cGMP and cAMP levels were measured in the cerebral arteries and bilateral parietal cortices. RESULTS: A significant vasospasm occurred in the cerebral arteries on both sides, more prominently on the right side. Concomitantly, rCBF on the right side was significantly decreased (P < .05). In the right MCA, cGMP levels were significantly lower than in the normal MCA (P < .05). After the administration of nitroglycerin for 3 hours, the cerebral vessels were significantly dilated on both sides (P < .05), and rCBF was significantly increased on the right side (P < .05) but not on the left side. Although depressed cGMP levels in the right MCA were not recovered by nitroglycerin, a significant increase in cGMP levels was observed in the basilar artery (P < .05). In both parietal cortices, cGMP levels were significantly decreased after SAH (P < .05) and unchanged after nitroglycerin treatment. There were no significant changes in cAMP levels in SAH and after nitroglycerin treatment. CONCLUSIONS: The vasodilator effect of nitroglycerin in spastic MCA may not be mediated by an increase in cGMP levels, suggesting an involvement of hyperpolarization of the smooth muscle cells. Given the increase in rCBF, nitroglycerin may be therapeutic for the treatment of vasospasm.

Animals↗
PubMed1996

New hydrolyzable tannins, shephagenins A and B, from Shepherdia argentea as HIV-1 reverse transcriptase inhibitors.

Two new hydrolyzable tannins, shephagenins A and B, were isolated along with hippophaenin A and strictinin from the leaf extract of Shepherdia argentea, which showed a remarkable inhibitory activity against human immunodeficiency virus (HIV)-1 reverse transcriptase. Their structures, having a gluconic acid core, have been elucidated on the basis of spectroscopic and chemical methods. The inhibitory effect of the leaf extract on HIV-1 reverse transcriptase was found to be due to tannins, and their activities were stronger than that of (-)-epigallocatechin gallate as a positive control.

Antiviral Agents↗
PubMed1996

Chemiluminescence response of cervine neutrophils to various stimuli.

The chemiluminescence response of cervine neutrophils to various stimuli was investigated in comparison with that of bovine and human homologues. The cervine cells showed a strong and consistent response, as observed in other species, to opsonized zymosan, phorbol myristate acetate and concanavalin A. The cells, however, like bovine homologues, failed to respond to n-formyl-methionyl-leucyl-phenylalanine which is a potent stimulant of human neutrophils.

Animals↗
PubMed1996

[The clinical value of BMIPP on the evaluation of myocardial ischemia and metabolism before and after CABG].

To evaluate the clinical usefulness of BMIPP (15-(p-[125I]-iodophenyl)-3-R, S-methylpentadecanoic acid), BMIPP and T1 imaging were underwent before and after surgery in 25 CABG patients. Preoperatively the demonstrated lesion on BMIPP scintigram is almost the same as that on rest-T1 scintigram. A month after CABG, the recovery on T1 scintigram was remarkable, however improvement on BMIPP was limited. These results suggest that on the evaluation of myocardial ischemia, the clinical value of BMIPP is almost the same as that of rest-T1 before CABG. The postoperative discrepancy between T1 and BMIPP scintigram suggests that the restoration of myocardial circulation does not directly improve myocardial metabolism.

Coronary Angiography↗
PubMed1996

[Diagnostic accuracy of 201T1 SPECT.MRI in brain diseases and inter-reader variance of diagnostic performance].

Fifteen-four studies of 201T1 brain tumor SPECT were independently interpreted by 9 nuclear medicine physicians with and without reference magnetic resonance images in 2 separate sessions to define an effect of referring images, and inter-observer variations. The physicians were requested to detect foci of abnormal deposits, and to discriminate whether they were malignant or not according to 5-grade scaling of subjective diagnostic confidence. Receiver-operating characteristics (ROC) analysis was performed. Mean sensitivity for presence of lesions (SEP), and sensitivity and specificity for malignancy of 201T1 SPECT were 84, and 53 and 55%, which were changed to 94, and 74 and 55% after referring to the MR images. The SFP was significantly improved (p < 0.05), but sensitivity and specificity for malignancy, assessed by areas under the ROC curves, were not significantly improved. Inter-observer variation of the SFP was significantly reduced with addition of the referring MR images. Cerebral lobar localization of lesions by SPECT showed great inter-observer variations (true localization ranged from 30 to 68.4%). It is concluded that 201T1 brain tumor SPECT has moderate sensitivity and specificity for malignancy, which is not improved by addition of anatomical reference images, that additional MR images reduce inter-observer variation of confidence on lesion presence, and that SPECT localization of lesions has great inter-observer variations.

Adolescent↗
PubMed1996

[A case report of concomitant carotid and coronary artery reconstruction].

We reported a case of a 70-year-old female who underwent simultaneous carotid endarterectomy and coronary artery bypass surgery. Preoperatively, cardiac catheterization demonstrated three vessel coronary artery disease. Her carotid angiogram revealed a 90% stenosis in the left common carotid artery. The cerebral blood flow scintigram on acetazolamide stress detected severely reduced cerebral blood flow on her left anterior and temporal lobe. Her postoperative course was uneventful. Postoperatively, no reduced cerebral blood flow was detected on the acetazolamide stress image. In patients with significant carotid artery stenosis, the cerearal blood flow scintigraphy on acetazolamide stress was a useful method for the simultaneous carotid endarterectomy and coronary artery bypass surgery.

Acetazolamide↗
PubMed1996

The development of a simple test method to characterise the compliance and viscoelasticity of long-term soft lining materials.

A simple test, based on the measurement of depth of penetration, has been devised to characterise long-term soft lining materials. Inter-laboratory testing has shown the method to be reproducible and to be capable of comparing and contrasting the compliance and viscoelastic behaviour of commercially available materials. Additional results emphasise the point that it is imperative to control the testing temperature, especially for the soft acrylic materials.

Acrylic Resins↗